Stallone, 67, said he was "deeply ashamed" after branding the teen a "rich little b---h" in a Saturday tweet that has since been deleted.

"To everyone and to David Hogg especially. I want to deeply apologize for my irresponsible words. I would never in a million years wish or promote violence to anyone anywhere on this planet," he wrote on Twitter Sunday. "After what these kids went through I'm deeply ashamed. Please accept my apology."

To everyone and to David Hogg especially. I want to deeply apologize for my irresponsible words. I would never in a million years wish or promote violence to anyone anywhere on this planet. After what these kids went though I’m deeply ashamed. Please accept my apology. Frank

Hogg, along with his fellow Marjory Stoneman Douglas High School classmates, has become a vocal gun control activist in the wake of former student Nikolas Cruz's Feb. 14 attack that left 17 dead and many more injured.

In the offending tweet, Stallone called him a coward and the "worst rep for today's youth."

"This David Hogg p---y is getting a little big for his britches. I'm sure someone from his age group is dying to sucker punch this rich little b---h," Stallone wrote. "Watch him run home like the coward he is. He's the worst rep for today's youth headline grabbing punk."

Frank Stallone apologized for calling David Hogg a “p---y” and a coward, among other things.(JESSE GRANT/GETTY IMAGES FOR PURE FLIX ENTER)

Stallone's eventual apology likely extended to Hogg's classmate and fellow activist Emma Gonzalez, who the actor called a "headline grabbing clown" in another deleted tweet.

The younger brother of Sylvester Stallone had briefly made his Twitter account private so that he would not "have to listen to a bunch of computer hero's (sic) telling (him) how tough they (sic) and I'm not," but made it public again hours later.

The flurry of tweets quickly caught the attention of the internet, where much was made of Stallone's career — or lack thereof.

"We don't have to worry about a Frank Stallone boycott. That started in the late seventies," director Judd Apatow wrote.

"What Frank Stallone said is despicable and I call on the Lomita Community Blood Bank to boycott him and no longer buy his plasma," actor Ike Barinholtz wrote.

Stallone's comments come after similar attacks on the students from conservative rocker Ted Nugent and Fox News host Laura Ingraham.

Nugent on Saturday called the student gun reform activists "mushy brained children who have been fed lies," and accused them of committing "spiritual suicide" in their fight for change.

Ingraham, meanwhile, mocked Hogg on Twitter for being rejected by several universities.

"David Hogg Rejected by Four Colleges To Which He Applied and whines about it. (Dinged by UCLA with a 4.1 GPA…totally predictable given acceptance rates.)," she wrote on Wednesday.

Hogg didn't take Ingraham's dig sitting down, however. The high school senior tweeted out a list of the biggest advertisers on Ingraham's show "The Ingraham Angle," and urged his followers to call the companies and demand they pull their ads.